This invention relates to vehicle door latches and more particularly to vehicle door latches that are capable of being locked from outside the vehicle.
Vehicle door latches customarily include a lock mechanism that prevents operation of the door latch so that the vehicle door cannot be opened by persons inside the vehicle unintentionally or by persons outside the vehicle who are not authorized. The door lock mechanism itself can also be operated from inside as well as from outside the vehicle.
The door lock mechanism is usually operated from inside the vehicle by a slide or a sill button that is actuated manually and also electrically in upscale vehicles. The door lock mechanism is usually operated from outside the vehicle by a key and key lock cylinder or some other device that keeps intruders locked out of the vehicle.
A long standing problem associated with lockable vehicle door latches is that of locking the keys inside the vehicle. This problem results from the door latch having the capability of being locked when it is unlatched. Thus the driver or passenger can lock the door by actuating the inside lock operator before the door is shut and avoid the inconvenience of using a key. Various solutions have been proposed for this "keyless" locking problem.
There are generally two types of mechanisms for locking the vehicle door latch. In one type, a locking member blocks and/or immobilizes a member of the latch mechanism so that the inside and outside door handles as well as the internal parts of the door latch cannot be moved.
One solution for the keyless locking problem in these blocking type door lock mechanisms is disclosed in U.S. Pat. No. 3,781,045 granted to Hans-Dieter Watermann Dec. 25, 1973 for a motor vehicle door latch with a lock mechanism that is only actuatable with the vehicle door closed. This known door latch has a detent or keeper that carries a fixed crank arm. The crank arm has a projection that prevents the lock mechanism from being engaged in all but the closed position of the door to prevent the user from locking his or her keys in the vehicle.
The second type of mechanism for locking the door latch is generally known as the free wheeling type. In this type, the lock mechanism disconnects the latching mechanism when it is engaged so that the motion of neither door handles is transferred to the detent lever and consequently operation of the door handles is ineffective. A vehicle door latch of this type is disclosed in U.S. Pat. No. 4,756,563 granted to Stephen L. Garwood and Jeffrey L. Konchan Jul. 12, 1988 for a vehicle door latch.
Solutions have also been proposed for the keyless locking problem in connection with vehicle door latches that have freewheeling type lock mechanisms. See for example U.S. Pat. No. 3,840,258 granted to Horst Brackmann Oct. 8, 1984 for a motor vehicle door latch and U.S. Pat. No. 5,054,827 granted to Jeffrey L. Konchan and Jiri Paulik Oct. 8, 1991 for a vehicle door latch.
These solutions, however do not prevent keyless door locking. They merely require actuation of the outside door handle or other outside latch operator with the hope that this extra operation will prevent unintentional locking of the keys in the vehicle.